In part 5 of my Linux soft synth tutorial, I look at the concept of modulation — changing synth parameters over time. We saw an example of this in part 4, where we used an envelope to control the volume of a sound over time; modulation extends this to other parameters, such as the pitch of the oscillators and the filter cutoff. Modulation can use envelopes to change parameters over the length of the sound — in fact, there’s a second envelope in Xsynth-DSSI just for modulation — or the low frequency oscillator, or LFO, to perform repeating rhythmic changes.

Modulation can produce effects ranging from subtle vibrato through to sweeping soundscapes and alien sound effects. Either way, it’s a powerful way to breathe life and movement in to what might otherwise be a dull sound.

High-res Ogg Theora version is here, or watch the Youtube version after the jump!

Due to the length of it all, the Youtube version is in two parts: